From 949670f8f46656a30ffbd22c9ae2cc645bda8533 Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Mon, 8 Jan 2024 15:02:29 +0000
Subject: [PATCH] dev/uart: Use a linker set to find uart classes

When the uart is configured via the environment we need to find the
uart class with a specified name. Currently to do this with an
incomplete list of uarts. As we may not have included all uarts in the
kernel each class is defined as weak.

Switch to a linker set so the list is always up to date based on what
is included in the kernel, and the class can be static.

Reviewed by:	imp
Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D43361
---
 sys/dev/uart/uart.h            |  4 ++++
 sys/dev/uart/uart_dev_ns8250.c |  1 +
 sys/dev/uart/uart_dev_z8530.c  |  1 +
 sys/dev/uart/uart_subr.c       | 12 +++---------
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/sys/dev/uart/uart.h b/sys/dev/uart/uart.h
index 5eae06ceba6..987152283c8 100644
--- a/sys/dev/uart/uart.h
+++ b/sys/dev/uart/uart.h
@@ -29,6 +29,8 @@
 #ifndef _DEV_UART_H_
 #define _DEV_UART_H_
 
+#include <sys/linker_set.h>
+
 /*
  * Bus access structure. This structure holds the minimum information needed
  * to access the UART. The rclk field, although not important to actually
@@ -99,6 +101,8 @@ uart_setreg(struct uart_bas *bas, int reg, int value)
  */
 struct uart_class;
 
+SET_DECLARE(uart_class_set, struct uart_class);
+
 extern struct uart_class uart_ns8250_class __attribute__((weak));
 extern struct uart_class uart_quicc_class __attribute__((weak));
 extern struct uart_class uart_z8530_class __attribute__((weak));
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c
index 090909fdf8d..f660639862f 100644
--- a/sys/dev/uart/uart_dev_ns8250.c
+++ b/sys/dev/uart/uart_dev_ns8250.c
@@ -451,6 +451,7 @@ struct uart_class uart_ns8250_class = {
 	.uc_rclk = DEFAULT_RCLK,
 	.uc_rshift = 0
 };
+DATA_SET(uart_class_set, uart_ns8250_class);
 
 /*
  * XXX -- refactor out ACPI and FDT ifdefs
diff --git a/sys/dev/uart/uart_dev_z8530.c b/sys/dev/uart/uart_dev_z8530.c
index 8e1adac0aec..107fcb1eb4b 100644
--- a/sys/dev/uart/uart_dev_z8530.c
+++ b/sys/dev/uart/uart_dev_z8530.c
@@ -309,6 +309,7 @@ struct uart_class uart_z8530_class = {
 	.uc_rclk = DEFAULT_RCLK,
 	.uc_rshift = 0
 };
+DATA_SET(uart_class_set, uart_z8530_class);
 
 #define	SIGCHG(c, i, s, d)				\
 	if (c) {					\
diff --git a/sys/dev/uart/uart_subr.c b/sys/dev/uart/uart_subr.c
index d10084cfa6d..e7570e17335 100644
--- a/sys/dev/uart/uart_subr.c
+++ b/sys/dev/uart/uart_subr.c
@@ -48,11 +48,6 @@
 #define	UART_TAG_XO	9
 #define	UART_TAG_BD	10
 
-static struct uart_class *uart_classes[] = {
-	&uart_ns8250_class,
-	&uart_z8530_class,
-};
-
 static bus_addr_t
 uart_parse_addr(const char **p)
 {
@@ -62,13 +57,12 @@ uart_parse_addr(const char **p)
 static struct uart_class *
 uart_parse_class(struct uart_class *class, const char **p)
 {
-	struct uart_class *uc;
+	struct uart_class **puc, *uc;
 	const char *nm;
 	size_t len;
-	u_int i;
 
-	for (i = 0; i < nitems(uart_classes); i++) {
-		uc = uart_classes[i];
+	SET_FOREACH(puc, uart_class_set) {
+		uc = *puc;
 		nm = uart_getname(uc);
 		if (nm == NULL || *nm == '\0')
 			continue;